Python面向对象

1. 基本

class Student(object):
    name = 'Student' # 默认值
    def __init__(self, name, score):
        self.score = score # public
		self.__name = name # private
 
    def set_name(name):
      self.__name = name
      
    def get_name():
      return self.__name

　　

2.继承

class Animal(object):
    def run(self):
        print('Animal is running...')
        
class Dog(Animal):
    def run(self):
        print('Dog is running...')


class Cat(Animal):
    def run(self):
        print('Cat is running...')
  
def run_twice(animal):
    animal.run()
    animal.run()　

运行示例：

>>> run_twice(Animal())
Animal is running...
Animal is running...
当我们传入Dog的实例时，run_twice()就打印出：

>>> run_twice(Dog())
Dog is running...
Dog is running...
当我们传入Cat的实例时，run_twice()就打印出：

>>> run_twice(Cat())
Cat is running...
Cat is running...　　

多态的好处就是：传参是谁，就调用谁的方法。彼此有继承关系。

object是所有类的继承父类。

 

3.判断继承关系

dog = Dog()
print(isinstance(dog, Animal)) # Animal

True　　

 

4.动态绑定函数

class Student(object):
    pass


def set_age(self, age): # 定义一个函数作为实例方法
     self.age = age

Student.set_score = set_score # 给Class增加function

s = Student()
s.set_score(100) # 可以调用

只给某个实例增加方法

from types import MethodType

class Student(object):
    pass


def set_age(self, age): # 定义一个函数作为实例方法
     self.age = age

s = Student()
s.set_score= MethodType(set_score, s) # 给实例绑定一个方法
s.set_score(100) # 可以调用

s2 = Student()
s2.set_score(100) # 不可以调用

 

5.枚举

from enum import Enum

Month = Enum('Month', 
	     ('Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'))


for name, member in Month.__members__.items():
    print(name, '=>', member, ',', member.value)

执行效果

('Jan', '=>', <Month.Jan: 1>, ',', 1)
...

 

枚举的其他例子

from enum import Enum, unique

@unique
class Weekday(Enum):
    Sun = 0 # Sun的value被设定为0
    Mon = 1
    Tue = 2
    Wed = 3
    Thu = 4
    Fri = 5
    Sat = 6　　

执行结果

>>> day1 = Weekday.Mon
>>> print(day1)
Weekday.Mon
>>> print(Weekday.Tue)
Weekday.Tue
>>> print(Weekday['Tue'])
Weekday.Tue
>>> print(Weekday.Tue.value)
2
>>> print(day1 == Weekday.Mon)
True
>>> print(day1 == Weekday.Tue)
False
>>> print(Weekday(1))
Weekday.Mon
>>> print(day1 == Weekday(1))
True
>>> Weekday(7)
Traceback (most recent call last):
  ...
ValueError: 7 is not a valid Weekday
>>> for name, member in Weekday.__members__.items():
...     print(name, '=>', member)
...
Sun => Weekday.Sun
Mon => Weekday.Mon
Tue => Weekday.Tue
Wed => Weekday.Wed
Thu => Weekday.Thu
Fri => Weekday.Fri
Sat => Weekday.Sat

　　

 

 参考资料

廖雪峰的Python教程

https://www.liaoxuefeng.com/